1. Field of the Invention
The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and apparatus for transmitting paging control information in a superframe-based wireless communication system.
2. Description of the Related Art
In the 4th Generation (4G) communication system, which is the next generation communication system, research and commercialization are being conducted to provide users with services having various Qualities-of-Service (QoSs) at a data rate of about 100 Mbps. In particular, an intensive study of the 4G communication system is now made to support high-speed services in the way of guaranteeing mobility and QoS for a Broadband Wireless Access (BWA) communication system such as wireless Local Area Network (LAN) system and wireless Metropolitan Area Network (MAN) system. A typical 4G communication system is an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system.
According to the IEEE 802.16 communication system standard, in case that there is no traffic to be transmitted/received during a constant time, a Mobile Station (MS) operates in an idle mode to minimize power consumption. In detail, in case that there is no traffic to be transmitted/received, the MS sends a De-REGistration REQuest (DREG-REQ) message to a serving BS, with which the MS is currently in communication, in order to operate in the idle mode. The serving BS receiving the DREG-REQ message sends the MS a De-REGistration Command (DREG-CMD) message to permit the MS to transition into the idle mode.
The DREG-CMD message includes a paging information Type/Length/Value (TLV) field. The paging information TLV field includes a paging group IDentifier (ID), a paging cycle and a paging offset.
The paging group ID is an identifier for identifying a paging group. The paging group is composed of a plurality of cells. The paging cycle is determined with reference to a paging cycle request sent by the MS. The paging offset is a parameter used when a time point capable of paging a specific MS using a frame number and the paging cycle is determined.
The MS awakes from the idle mode at a time point indicated by the paging offset, receives paging control information (e.g., the paging group ID and a paging indicator) during a paging listening interval, and receives a paging message using the received paging control information.
At present, the IEEE 802.16e standard defines a technology for transmitting paging control information in the idle mode. The technology for transmitting the paging control information may also be applied to an IEEE 802.16m system, which is an evolution of the IEEE 802.16e system. However, unlike the IEEE 802.16e system that operates on a frame by frame basis, the IEEE 802.16m system operates on a superframe by superframe basis composed of several frames, and transmits SuperFrame Header (SFH) information based on the superframe. Thus, there is a need for a method and apparatus for transmitting paging control information considering the superframe of the IEEE 802.16m system.